One of the key components of the polymer electrolyte membrane fuel cell (PEMFC) is the polymer electrolyte membrane (PEM). The PEM is a proton-conducting polymeric solid that provides a proton transport vehicle between the anode and the cathode, while simultaneously serving as a barrier to prevent intermixing of the fuel and oxidant streams. Besides these proton transport and gas barrier properties, the PEM needs to satisfy other essential requirements for the appropriate operation of the fuel cell, including: low electrical conductivity, water transport, high hydrolytic stability, and excellent mechanical integrity, among others.
Over the past years, research endeavors have focused on developing new cost-effective and operationally sound PEM materials with the purpose of closing the gap between the actual PEMFC technology (based primarily on perfluorosulfonic acid (PFSA) membranes) and commercialization targets (e.g., DOE targets for portable fuel cells). Numerous approaches are being considered in the development of these new PEM materials, including: modification of PFSA-based membranes, functionalization of high-performance hydrocarbon polymers, polymer blends of inert and ionic conductive precursors, and organic/inorganic composite membranes, and organic/inorganic composite or hybrid proton exchange membranes.
PEMs from semi-interpenetrated networks of poly(vinylidene fluoride) (PVDF) and covalently-cross-linked sulfonated acrylic polyelectrolytes have been shown to exhibit acceptable proton conducting and mechanical properties comparable or better than NAFION standards.
There is a need to further improve the conductivity and mechanical properties of the PVDF/PE membranes.
Surprisingly, the addition of nanofillers, and especially zirconium-based nanofillers into polyvinylidene fluoride (PVDF)/polyelectrolyte blends produces organic/organic/inorganic tri-phase PEMs having improved conductivity and mechanical properties.